Figure 7-6 is a drawing of a typical welded steel truss. When you interpret
the welding symbols, you will see that most of them show that the structural
angles will be fillet welded. The fillet will have a 1/4-inch radius (thickness)
on both sides and will run along the angle for 4 inches.

RIVETED STEEL STRUCTURES

Steel structural members are riveted in the shop where they are fabricated to
the extent allowed by shipping conditions. During fabrication, all rivet holes
are punched or drilled whether the rivets are to be driven in the field or in
the shop.

Figure 7-6.-Welded steel truss.

Go to figure 7-7 and look at the shop fabrication drawing of a riveted steel
roof truss. At first look, it appears cluttered and hard to read. This is caused
by the many dimensions and other pertinent facts required on the drawing, but
you can read it once you understand what you are looking for, as we will explain
in the next paragraphs. For example, note the following specifications in view
A:

The top chord is made up of two angles labeled with specification 2L 4 x 3
1/2 x 5/16 x 16'-5 1/2" . This means the chord is 4 inches by 3 1/2 inches by
5/16 inch thick and 16 feet 5 1/2 inches long.

The top chord also has specification IL 4 x 3 x 3/8 x 7(e). This means it has
five clip angles attached, and each of them is an angle 4 inches by 3 inches by
3/8 inch thick and 7 inches in length.

The gusset plate (a) on the lower left of the view is labeled PL 8 x 3/8 x
1'-5"(a). That means it is 8 inches at its widest point, 3/8 inch thick, 1 foot
5 inches long at its longest point.

The bottom chord is made up of two angles 2 1/2 x 2 x 5/16 x 10'-3 7/16",
which are connected to gusset plates a and b, and two more angles 2 1/2 x 2 x
1/4 x 10'-4 1/8", which are connected to gusset plate b and continue to the
other half of the truss. Two more angles are connected to gusset plates c and b
on the top and bottom chords; they are 2 1/2 x 2 x 1/4 x 2'- 10 1/2". The other
member between the top and bottom chords, connected to gusset plate b and the
purlin gusset d, is made up of two angles 2 1/2 x 2 x 1/4 x 8'-5 ".

View A also shows that most of the rivets will be driven in the shop with the
exception of five rivets in the purlin gusset plate d and the two rivets shown
connecting the center portion of the bottom chord, which is connected to gusset
plate b. These seven rivets will be driven at the jobsite. Figure 7-8 shows

Figure 7-8.-Riveting symbols.

conventional symbols for rivets driven in the shop and in the field.

Figure 7-7, view B, shows the same truss with only the names of some members
and the sizes of the gusset plates (a, c, and d) between the angles.

Figure 7-7, view C, is the same truss with only a few of the required
dimensions to make it easier for you to read the complete structural shop
drawing.

DRAWINGS OF STEEL STRUCTURES

Blueprints used far the fabrication and erection of steel structures usually
consist of a group of different types of drawings, such as layout, general,
fabrication, erection, and falsework. These drawings are described in the
following paragraphs.